Le 15/04/2017 à 15:55, songbird a écrit :
maybe grub needs something provided by the modules: usbms, ehci, uhci or ohci?
Be careful if you're going to use driver modules (USB, PATA, AHCI...) to get direct access to a device. It disables access to *all* devices through the BIOS, including the device GRUB was booted from and reads its own files.